The present invention relates generally to the field of audiometric apparatuses and associated screening methods. In particular, the invention relates to audiometric apparatuses and auditory screening methods for providing rapid, low-cost, comprehensive, non-invasive screening of a subject's hearing.
Language acquisition in infants requires a critical period of hearing capacity which spans the frequency range of human speech. The critical period extends from birth to about two to three years of age, when infants typically begin to talk with some level of proficiency.
Approximately three to five percent of newborn infants suffer from some degree of hearing impairment. These impairments can be devastating to the social, emotional and intellectual development of the affected infants. Early identification of hearing impairments in infants allows for early intervention to minimize significant speech and language deficiencies. Infants are usually unable or unwilling to participate in known behavioral auditory examinations. Moreover, delaying auditory screening until infants can verbally respond is often too late for hearing impaired infants and results in long term problems.
Federal, state and private agencies have attempted to implement universal auditory screening of infants for over twenty years. A major impediment to the implementation of universal auditory screening of infants has been the cost and complexity associated with the tests. Current infant screening tests are time consuming and require expensive devices and trained specialists to conduct the tests and interpret results. As such, universal auditory screening of infants is presently economically infeasible.
Various entities have developed audiometric devices which may be useable for screening an infant's hearing. These existing devices generally fall into one of two categories. Devices in the first category are configured to elicit auditory evoked potentials (AEPs), which are electrical responses of cells within the auditory pathway of the brain to an acoustic stimulus. Such devices typically utilize the non-invasive auditory brainstem response (ABR) test for auditory screening of infants. An earphone provides an acoustic stimulus, specifically a brief click or toneburst, to the subject's ear. Electrodes attached to the subject's scalp receive auditory evoked potentials from the scalp, which are recorded as an electroencephalogram waveform. Analysis of these brainwave patterns are used to determine if the auditory system is functioning normally.
Devices in the second category utilize the evoked otoacoustic emission (OAE) test for auditory screening. An earphone provides a brief acoustic stimulus to the subject's ear. A microphone disposed in the subject's ear adjacent the earphone receives an OAE from the ear, which is recorded as an acoustic signal. Analysis of the OAE waveform provides an indication of the functional integrity of the middle and inner ear, which together comprise the auditory periphery.
A number of limitations exist with respect to existing audiometric screening devices. One limitation is that some existing devices are complicated and require extensive training to operate. Another limitation is that other devices only provide a pass/fail indication and lack a visual display. Yet another limitation is that two separate devices are required to perform both the ABR or OAE tests. An operator typically makes a subjective determination of the acceptability of the ABR or OAE test results based on a visual examination of the response waveforms. Because existing audiometric devices do not allow for rapid, low-cost, non-invasive, comprehensive screening of infants, such devices do not adequately address the need for universal auditory infant screening.